Fertilizing non-soil

roseblush1(8a/Sunset 7)September 6, 2011

I just finished reading the thread about signs of over fertilizing and saw some very informed answers and started thinking about my garden and am looking for some input, but didn't want to hog the other thread.

I garden in glacier slurry, which is non-soil. My house pad and gardening area were cut out of a slope. I've gone about creating the rose garden all wrong, but that's not the issue I want to address here.

When I bought my house in '04, the soil was dead. It was covered with weed barrier and decorative rock. Since I could not afford to have all of the yard escavated and new soil brought in, I ended up digging holes in the glacier slurry to plant the roses. I screen out all of the rocks and added lots of compost to the natural soil and planted the roses. In the first years, I used organics to feed the plants, mulched twice a year and watched the plants kind of limp along.

It finally dawned on me that the garden level is four feet down from where the natural top of the soil where plant debris from nature would have fed the soil. In other words, it was highly unlikely that there was any organic plant material in the soil, other than what I had added.

I've been told it takes at least 10 years to build up soil to where it can provide nutrients to plants. Last year, I tried a chemical fertilizer, and the garden looked completely different. The plants were no longer limping along, but were actually thriving.

We get on average 40" of rain each year, with hot dry summers. Drainage in glacier slurry is not a problem as it is very porous. .. no puddles no matter how hard or long it rains.

How would you go about fertilizing plants in non-soil ? And what strength of fertilizer should I use ?

Organic matter is transient in the soil, as bacteria eat it up. More OM will be continuously supplied to the upper topsoil if you maintain a good mulch of any organic material. My suggestion is that the problem with your native soil may be not so much the lack of organic matter as the coarseness of the mineral particles. Sand and gravel are non-nutritive, don't hold added nutrients, and drain too fast. It would be interesting to do a jar test (google this) to see how much silt and clay are present.

In addition to the compost, you can add clay as plain cat litter, 10-15% by volume, to future rose holes and replants. I have found this really helps my soil, which naturally is a mixture of silt and sand.

Meanwhile, if your soil is mostly sand and gravel, you need to add nutrients continuously. I would suggest a good quality coated timed-release fertilizer such as Osmocote with a nutrient ratio between 1-1-1 (eg 14-14-14) and 3-2-1 (eg 18-6-12). It should contain trace and minor elements. Follow the label directions for whatever fertilizer you use.

It's always a good idea to get a soil test to check pH and any unusual excesses or deficiencies of nutrients. For example, if the soil is deficient in magnesium, you have to supply that in addition to a "complete" manufactured fertilizer.

Lyn: I don't have glacier slurry, but I can give you answers from folks who grow plants in potted medium with thin layer of soil mixed with peat poss.

From High Country Rose, who gave me the healthiest bands, like over 1 foot tall Pat Austin with a 4" bloom. Here's THEIR secret to tall plants in tiny bands:

"We use Daniels fertilizer (liquid) on our roses and our soil has mycorrhizone in it."

Daniels fertillizer is also used by other large nurseries. It's 40% lower in salt and soy-based. The ink on your newspaper is also soy-based, and people report worms loving that stuff.

The other expert is University of Kentucky, College of Agriculture. Their research is entitled "Organic Fertilizers and Composts for Vegetable Transplant Production" - I grow both tomatoes and roses, they are similar in being deep-rooted, like well-drained but fertile soil. You can read their research at:

The differences between chemical and organic fertilizer are: 1) chemical is faster, but higher in salt
2) chemical leaks out of the water, and does not build up nor improve your soil 3) you have to water the plants more if you use chemical

The downfall of organics can be seen from the above U of Kentucky research, such as: bagged compost cow manure came with a low pH of 4, versus a high pH of 8.21 for composted horse manure - the potted soil medium MetroMix 500 is best with pH at 5.29.
In that experiment, the chemical fertilizer Peter's 20-10-20 came out ahead of the organics: The plants with Peter's were green and tall, the plants with cow manure slowed down and yellowing started to occur, the plants grown in worms and horse compost, or the NO fertilizer control were stunt, including purple stems, yellow and dead leaves at the base.

My conclusion: if you have the advantage of porous, super-well drained soil, plus plenty of rain - then go with chemical fertilizer, it's faster.

I stick with organics since my soil is heavy clay, poor drainage, and whatever salt I put in from chemical fertilizer stays there longer. My logic is: Why should I give excess salt to my plants, they get thirsty and I have to waste time watering them?

Folks who live in a dry, hot region plagued with drought would do better with organics, since they have less salt, improve the soil, and hold moisture better. My favorite stuff to acidify the soil is peat moss (1 to 2 inches mixed with the top 6" of native soil can lower pH by one point). The second favorite is alfalfa meal with root-stimulating hormone, I mix with flaky horse manure and use as mulch.

We don't know the damage of chemicals to the environment until later. One example is aluminum sulfate, once recommended to acidify the soil. Now it's known that excess aluminum kills plant roots, and the experts recommend sulphur or peat moss instead.

My home sits on a glacial moraine also. The glacers stopped here and as they melted they left a deep bed of sand and gravel. Wells drilled 40 feet down are still in the sand and gravel
I moved here ten years ago. Since then I've added copious amounts of horse manure as mulch. Oak leaves, which are plentiful here are piled in the beds each fall and left there in spring to break down for organic matter.
I've mulched with wood chips a number of times having added another four inches this year. Grass clipping are left on the lawn along with weeds which are tossed on the grass to be chopped up by my lawn mower. I mulch the leaves in the fall into tiny pieces and leave them also.
The yellow sand I had when I moved here is now black organic filled soil. I use an organic fertilizer mix with the same ingredients used in Mill's Magic Rose Mix.
Sandy soil can be improved without having to haul in top soil from elsewhere. This top soil is seldom that. It's more often black subsoil scrapped away from mall or subdivision building sites and requires building up with organics also.
I do apply a high nitrogen fertilizer once a year for a quick pick me up for the roses. The organics help keep it from being quickly leached away.
My only complaint is even after a few inches of rain, it drains quickly. After the sun comes out, the soil dries fast. The plants show lack of water distress within a few days.
Luckily, our water table is only 10-15 feet down so I have plenty of water to irrigate.

Before I start responding to the above posts -- a big thank you -- I think I need to describe my non soil better. I have been using the local term "slurry" when I should have used the term "till" or "debris". Glacier activity actually stopped at a higher elevation of 3,000 feet (I am at 2000 ft), so the slope itself was created by the run off as the glacier melted. The house pad and gardening area was cut out of that slope.

The soil consists of tightly compacted stones, larger than gravel, but smaller than my fist with no sharp edges, and clay/silt.

Michaelg - you are right about the soil not being able to hold nutrients. If I were to do your jar test, I would say that the soil is 4/5 stones and 1/5 clay. I can say that because I've dug enough holes and screened out the rocks and ended up with lots more rock than clay. From the feel of the moist "soil" once the rocks are removed, there is very little sand.

Strawberryhill - I've tried the alfalfa pellets and other organics from the feed store and time released fertilizers and the plants just didn't seem to get enough of anything until I switched to chemical fertilizer last year. I don't think I need to worry about salt buildup. I think rain water finds a way through the stones and eventually ends up in the underground streams that feed the river. My glacier till is not like hardpan where the water is trapped. I would prefer not to use chemical fertilizers because I think everything ends up in the river.

Karl - I've mulched with oak leaves and other types of leaves that I have gathered, like madrone, gleanings of alpha hay from the feed store, clean wood chips, pine needles, grass clippings from my front yard since '05. The soil in the beds has not improved because I did not remove all of the stones.

This year, when I started to put down a heavy layer of wood chips, it became obvious that my roses have sunk and the crowns of the roses are significantly lower than the surface of the surrounding beds - something I truly did not expect. I am going to have to "grade" the beds so that all of the expected rain water due this winter doesn't all drain into the rose holes and rot the roses. That tells me putting stuff on top isn't going to improve my soil.

Just the thought of doing that work along with the regular fall chores is kind of defeating, but I am not ready to give up my roses. I haven't got a plan going forward and will be looking for advice there, too, but I thought I'd go one step at a time and start with the fertilizer question.

Thank you all for taking the time to give me added information so that I can start working on a plan for next year. The fertilization question has been bothering me all summer.

"I would prefer not to use chemical fertilizers because I think everything ends up in the river."

What you might need to worry about here is excessive nitrogen in any form. Nitrogen that isn't taken up by plants evolves to nitrate, which leaches downward and can contaminate groundwater.

However, the chemicals in manufactured fertilizer also occur or evolve in organic fertilizer and organic matter generally. That is, even if you start with an organic protein source, bacteria will turn it into urea > ammonium > nitrite > finally nitrate. Manufactured fertilizer will contain one of these four forms of nitrogen.

Superphosphate doesn't readily occur in natural soils, but as soon as you apply it, it forms compounds that do commonly occur in natural soils. And phosphates don't leach out if there is any clay present.

You might want to determine whether the fine material in your soil is clay or silt.

Lyn: you are right about alfalfa pellets DO NOT work. See the thread started by Melissa "Rethinking alfalfa in California". Alfalfa meal works better, but ONLY if mixed with a medium - such as 2 cups per planting hole mixed with soil as Roses Unlimited suggests. I mix alfalfa meal with horse manure to solve the low-nitrogen problem (horse manure is bedded on straw, saw dust, hay - which deplete nitrogen). I would prefer blood meal, but I am stuck with a huge bag of alfalfa meal from the feed store. It works wonder in breaking up clay soil, very much like what peat moss does.

I dumped blood meal around trees to solve the nitrogen-fixing-weeds problem (over a decade of doing so, no problems). One time I dumped blood meal around marigolds to deter rabbits from my veges. The marigolds grew to 2 ft. tall, super green & bushy, but zero flowers.

There's the phosphorus-burn (or tip burn) problem associated with bonemeal, and superphosphate. Chemical fertillizer is better in this regard, because you know exactly the amount you are getting, versus a rough estimate for organics.

As to roses being sunken low due to the stuff you add on top, check out Roseek (Kim)'s info. on how to lift the crown up in the forum "what's the best rootstock for heavy clay?"

What I would do is mulch with a good quality compost or other organic material at least once if not twice every year without fail, and use the chemical fertilizers in as small amounts as possible that give you the results you want. After a while with the breakdown of the mulch over time you may find less and less chem fertilizer does the same job. Keep it simple. Rose growing ain't rocket science.

The major problem with chem fertilizer is when people heavily fertilize their lawns and the run off goes into a nearby stream, river, or other body of water, causing an algae bloom that then kills all the fish. If that's not an issue in your situation, don't worry about it.

Thank you all for your input. As I have written about my "soil" and read your comments about fertilizing, I have gotten a clearer picture of what I am doing right, where I can improve and what not to worry about.

I finally realized that I am gardening in sub-soil. There is no nitorgen to be robbed by anything I put on top of it and I'll need to use chemicals until the soil matures.

Kim and I have been talking about my sinking roses and I know I am going to have to dig them all up and, in a sense, start over, but for this season, I am just going to make sure that the winter rains do not drain into the rose holes. Next year, I'll have dig them up and mound the beds and replant them.

It sounds like more work than I want to do, but knowing me once I get started, I won't be thinking about that at all.

Lyn: For my case, Kim's procedure of lifting the crown up to solve the "wet-feet" syndrome of plants in my heavy clay worked well.

I did that a decade ago with my 5' tall white pine trees. They got wet feet from the heavy rain, plus being buried by the extra soil I dumped on top. I lifted all 4 up. First I dug a circle around the tree. I jacked up one side, using a long shovel under the rootball (hold this shovel up with bricks). Then I used a second shovel to dig up the other side. The rest is filling the cracks with soil to hold the rootball in place.

The four trees didn't mind a bit. A year later, I repeated the procedure, no problems whatsoever.

I had removed the rootballs COMPLETELY from the holes of many plants, including many perennials and 4 Knockout roses. Each time I removed the root ball from the hole, no matter how small it is, it was very stressful to the plants. The Knock-outs took at least 2 months to recuperate.

When you lift the root ball COMPLETELY from the soil, the dirt crumbles and damage the small feeder roots. When you jack up the rootball with 2 shovels, the root ball is intact, and you don't damage feeder roots, as long as you cut up a circle in advance. The two shovels are used for symmetry, so you don't end up with the plant being sunken or lopsided on one side.

Most trees cannot tolerate a change of grade, but roses can. Feeder roots and eventually a new crown will develop in the upper topsoil where they want to be.

When northern growers plant grafted roses, they may bury the natural crown and fleshy roots as much as a foot below where they grew in the field. (The natural crown is the area where the roots diverge, and it develops just a few inches under the surface.)

I have added soil over roses where the soil subsided to expose the bud union, and the roses didn't react to that at all. And as I said above, a reliable poster reported some years ago that he had successfully added 4" of new soil to established roses all at once.

You are both correct about the expected damage to the feeder roots when I "dig" up these roses. I really blew it when I planted them because I did not understand the nature of glacier till.

It is totally impossible to dig with a shovel in this stuff, even when it is moist or very wet. The stones are so tightly compacted that the only tools which can be used for digging are a digging bar, a pick or a mallet. (I use a short handled mallet when I get deeper into the rose hole.)

I did find a site that taught me how to do the jar test correctly. The test takes about three days. So far, I have little sand or silt in the soil once I remove the stones, so it looks like the soil between the stones is mostly clay.

I dug big, wide holes when I planted the roses and I am certain, since they have been there for several years, the plants have put out roots beyond the holes and into the glacer till. Those roots will be damaged when I lift the roses.

Over the years, I have added soil to the rose holes and that's why I didn't realize how much they had sunk until I started to put down my winter mulch this year.

I have perfect drainage in that even when it rains hard for days during the winter, there are no puddles of water anywhere on the house pad level .. not even in the depressed rose holes.

For now, I am creating a barrier around the rose holes to keep the mulch from sliding down into the holes and covering the crown of the roses. As I remove soil from the beds and sift out the stones, I am putting it in a pile mixed with all of the organic materials I can glean so it will be ready for use next spring. I am also creating a raised bed for the smaller roses, which will leave me room to plant some larger roses that have been on my want list for a long time.

I am thinking I have to move the roses out and create some top soil to put back into the bed in order to make the area more rose friendly. I think I only have to rework the top 6 to 12 inches and then put in better soil to raise the surface of the beds up so I can plant in them again. Otherwise the beds will look more like pits instead of the rose beds I'd like to see.

This is my tentative plan. I just don't see an easy way to fix my mistake. The good news is that all of the plants are healthy, so I think I won't lose any of them if I get the work done before the heat hits next year.